More and more services are being deployed over accesses to a packet communications network, e.g. the Internet, regardless of whether the services are fixed or mobile. By way of example, these services include voice calls, video file transfers, games, and web type services. By their nature, they have quality-of-service requirements that differ in terms of delay and packet loss rate.
The European patent application published under the number EP 2 031 809 proposes a method of processing flows that enables differentiated processing to be implemented on data flows at a point in a communications network. Data packets belonging to different flows are received by a device of the communications network and they are stored in a queue for onward sending by the device. In order to send a data packet, a flow is selected having the least memory space allocated thereto in the queue, and a packet of the selected flow is extracted from the queue and sent, and when the memory space available in the queue does not enable a received packet to be stored, a flow is selected to which the most memory space in the queue is allocated and a data packet of the selected flow is deleted from the queue. That differentiated processing of the packets does not require the packets belonging to the various flows to be explicitly marked. It enables differentiating service levels to be provided, seeking to send certain types of flow on a priority basis in implicit manner, i.e. without explicitly determining the associated applications.
Consideration is given below to a device in which one of the interfaces is of the wireless type, i.e. operates by radio, and for which access to the radio resource is time-shared between various users. Various users or pieces of equipment are connected via the wireless interface to the device. When the link between one of the pieces of equipment and the device is subjected to poor radio conditions, a low data rate is selected and consequently the time required for sending a packet will be longer. Because access to the radio resource is time-shared, that longer time retards the sends of all of the packets waiting in the device. Thus, as soon as one user is subjected to poor radio conditions, the other users are also penalized.
In operation, the device receives packets belonging to different flows for different users on one of its interfaces and it sends them to the destination users of those flows via the wireless interface. The above-described flow processing method does not enable good performance to be obtained under such circumstances. By way of example, for two users A and B, each having an ongoing flow of the same type, e.g. a video file transfer in “streaming” mode, the respective flows of those two users A and B will be differentiated by the flow processing method relative to any other non-real time flows of those users and processed on a priority basis. If user A is subjected to radio conditions that are poor compared with those of user B, then the flow of user B will be penalized by the flow of user A for the reasons set out above. The implicit differentiated processing between flows as proposed in document EP 2 031 809 therefore does not enable good performance to be obtained in terms of scheduling packets for sending over a radio interface having time-shared access.